public static void main(String[] args) {
ListNode head = new ListNode(1);
head.next = new ListNode(4);
head.next.next = new ListNode(3);
head.next.next.next = new ListNode(2);
head.next.next.next.next = new ListNode(5);
head.next.next.next.next.next = new ListNode(2);
partition(head, 3).print();
}
public static ListNode partition(ListNode head, int x) {
ListNode dummy = new ListNode(-1);
dummy.next = head;
ListNode pre = dummy;
ListNode append = dummy;
while (head != null) {
if (head.val < x) {
if (append.next != head) {
pre.next = head.next;
head.next = append.next;
append.next = head;
append = append.next;
head = pre.next;
} else {
append = append.next; // head
pre = head;
head = head.next;
}
} else {
pre = head;
head = head.next;
}
}
return dummy.next;
}